1. Field of the Invention
The invention relates to a crosslinkable silicone mixture which contains a ferrocene compound and an alkoxysilane having at least one epoxide group.
2. Description of the Related Art
Electronic components are being operated at ever greater powers and the power density continues to increase as a result of progressive miniaturization. Power electronics in particular requires new materials which withstand a temperature of above 200° C. in the long term and afford long-term protection against environmental influences for the power semiconductors embedded therein and ensure insulation performance. The silicone gels used to date in the field of power modules do not meet this requirement since thermooxidative embrittlement occurs above about 180° C. and allows the gel to harden; in addition, delamination and bubble formation of the embedding gel from the substrate to be protected is observed.
MX 9702803 describes fluorosilicone gels which are heat-stabilized by addition of ferrocene or ferrocene derivatives, so that the mechanical properties are largely maintained under the action of heat.
Fluorosilicone gels which have been heat-stabilized by means of ferrocene or ferrocene derivatives have been described. However, pure heat stability does not suffice for protection of electronic components, i.e. the pure stability of the usually low modulus of the crosslinked silicone is not sufficient to protect the electronics to a satisfactory extent. Rather, the delamination and bubble formation of the embedding mixture which occurs at such high temperatures has to be prevented.